Rayleigh Criterion Calculator
Enter wavelength and aperture diameter to find the minimum angular separation your optic can resolve.
Optical Parameters
Visible light: 380 nm (violet) — 750 nm (red). Green ~550 nm.
Lens or mirror diameter. Larger aperture = better resolution.
When set, calculates minimum resolvable separation at this distance.
Rayleigh Criterion
θ = 1.22 × λ / D
θ in radians, λ = wavelength, D = aperture diameter (same units).
Quick examples
Summary
Enter wavelength and aperture diameter to find the minimum angular separation your optic can resolve.
How it works
- Enter the wavelength of light (in nm, µm, or m).
- Enter the aperture diameter of your optical system.
- Select the unit for the aperture (mm, cm, m, or inches).
- The calculator applies θ = 1.22 λ / D and outputs the minimum resolvable angle.
- Results are shown in radians, arcseconds, and arcminutes for easy reference.
- For telescopes, the minimum resolvable separation at a given distance is also displayed.
Use cases
- Determine if a telescope can separate two closely spaced stars.
- Check the diffraction-limited resolution of a camera lens.
- Compare optical systems by their theoretical resolution ceiling.
- Plan microscopy experiments requiring specific spatial resolution.
- Estimate the detail visible on a planet surface through a given aperture.
- Evaluate whether atmospheric seeing or diffraction is the limiting factor.
Frequently Asked Questions
Last updated: 2026-07-24 ·
Reviewed by Nham Vu